The huge majority of bicycles sold and available in the marketplace today are of the diamond frame type or derivatives that maintain the substantially upright riding position. Recumbent bicycles which place a rider in a supine orientation have been available for years but despite offering many advantages to diamond frame type bicycles (such as but not limited to more comfortable riding position, and lower wind resistance) have been unable to capture a substantial portion of the bicycle market.
One of the potential reasons for the relative failure of recumbent style bicycles compared to traditional bicycles has been their much greater cost. The huge numbers of diamond frame and derivative bicycles produced permit manufacturers of the bicycles and associated components to take full advantage of manufacturing economies of scale. In contrast, the relatively low demand for recumbents drives up the cost of recumbent components such as the frame, the wheels, and the seat.
In 2004, the inventor of the present invention was awarded an innovation patent No. 2004100489 ('489) from the Australian Patent Office for a “Bicycle Front Wheel Drive Assembly and Adjustable Rear Dropouts”. The patent describes an assembly that can be used in conjunction with a standard diamond frame or a derivative frame bicycle to create a recumbent bicycle. Since most of the components of the bicycle are used save for the seat, the total cost of converting a traditional bicycle to a recumbent with the assembly and an associated recumbent seat is substantially less than purchasing a recumbent bicycle.
The original design, although functional, has several drawbacks. First, in '489 design, the front wheel is attached at an intermediate location along the forward chainstays. Because of the relatively small diameter of the forward chainstays as necessitated by the design, the material in the stays can be subject to significant stress and strain potentially subjecting the chainstays to premature failure, usually bending. The intermediate location of the wheel attachment also increases the amount of flex of the chainstays when subject to ground loads. The flexure can be disconcerting to a rider as well as have deleterious effects on the bicycle's stability.
The location of the relocated front drive wheel in the forward chainstays also increases the difficultly in adjusting an associated bicycle for riders with different length legs. Specifically, when the assembly's telescoping tube is lengthened or shortened to accommodate differing leg lengths, the forward chainstays necessarily rotate about the connection locations with the front fork, causing the forward section of the bicycle frame relative to the wheel to be lowered or heightened respectively. It is desirable to have the axles of the respective front and rear wheels approximately equidistant from the ground but any height adjustment would throw off such a balance requiring the use of a pair of rear wheel height adjustment brackets to permit a user to adjust the rear wheel's axle height after the front wheel's height has been changed. Further, the relative change in positioning of the front wheel due to a leg length adjustment may require adjustment of the front brake pads. Needless to say, the recumbent bicycle of the '489 patent is not friendly to rapid adjustment for riders of differing statures and is best set up for a single rider.
Another drawback of the '489 design concerns the connection of the telescoping tube and the associated gooseneck tube to the head tube of the associated bicycle frame. Simply, because the mounting bracket, to which the telescoping tube is pivotally coupled with the gooseneck, is fixedly secured to the gooseneck, the angle of the telescoping tube must change its relative angular orientation as the telescoping tube is lengthened or shortened. Since the front derailleur is attached to the telescoping tube, any angle change of the telescoping tube may require adjustment of the front derailleur's location and/or angular adjustment of the front derailleur's cage.